Viridian Energy unveiled Wednesday a new plan called “minus-5” through which it guarantees electric and natural gas prices 5 percent below those offered by utilities in the 12 markets the company serves, including Connecticut.

Viridian and parent company Crius Energy are based in Stamford, with the company relying on independent agents to sell its plans.

Minus-5 plan rates fluctuate with those of utilities but are guaranteed to stay 5 percent below utility rates as measured by indexes Viridian maintains. Viridian says more than half of the electricity it sells under the plan is generated from renewable resources, and that natural gas sold is backed by carbon offsets representing 25 percent of natural gas customers’ total usage.

In mid-September, Viridian announced an agreement with Sungevity to sell photovoltaic energy systems in Connecticut and other states. Viridian had previously marketed systems from SolarCity.